Ensure statement is not optimized "away"

Question

I'm using an API where, unfortunately, calling a get property accessor has a side-effect. How can I ensure that:

public void Foo()
{
  var x = obj.TheProp; // is it guarnateed to be accessed?
}

isn't optimized away by the compiler?

Answer 1

That will not be optimized away - the getter is a method and will be invoked, although the JIT might choose to "inline" a lot of it if it is simple, perhaps eventually (and entirely theoretically) ending up with just a null-reference check if TheProp doesn't do anything particularly exciting. What can happen is that the "thing returned" (that the code stores into x) is eligible for garbage collection before the method ends; this is rarely an issue, except with things like an out-of-process mutex; in which case, you can do things like:

var x = obj.TheProp;
// long-running code here
GC.KeepAlive(x);

Note, however, that if x is value-typed, this will force it to be boxed, which is not ideal.

Emphasis, though: the above is not intended to ensure that TheProp is actually invoked; it is for a specific set of garbage-related scenarios.